package com.cscp.javastudy.juc.pc;

/**
 * 线程之间的通信问题，生产者和消费者问题
 * 线程交替执行， A B 操作同一个变量 num=0
 * A num+1
 * B num-1
 */
public class A {

    public static void main(String[] args) {
        Data data = new Data();

        //线程A
        new Thread(() -> {
            for (int i = 0; i < 10; i++) {
                try {
                    data.increment();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
             }
        },"A").start();

        //线程B
        new Thread(() -> {
            for (int i = 0; i < 10; i++) {
                try {
                    data.decrement();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        },"B").start();

        //线程C
        new Thread(() -> {
            for (int i = 0; i < 10; i++) {
                try {
                    data.increment();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        },"C").start();

        //线程D
        new Thread(() -> {
            for (int i = 0; i < 10; i++) {
                try {
                    data.decrement();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        },"D").start();

    }

}


/**
 * 资源类
 */
class Data{

    private int num = 0;

    public synchronized void increment() throws InterruptedException {
        while (num != 0){
            //等待
            this.wait();
        }
        //通知其他线程，我+1完毕了
        num++;
        System.out.println(Thread.currentThread().getName()+"=> "+num);
        this.notifyAll();
    }

    public synchronized void decrement() throws InterruptedException {
        while (num == 0){
            //等待
            this.wait();
        }
        //通知其他线程，我-1完毕了
        num--;
        System.out.println(Thread.currentThread().getName()+"=> "+num);
        this.notifyAll();
    }

}
